Although Smaug was the greatest of the dragons of his day,[7] he seems not to have been the last of his kind as Gandalf told Frodo that "there is not now any dragon left on earth in which the old fire is hot enough [to melt the Rings of Power]",[8] indicating the presence of other, lesser dragons.

Characteristics

Taxonomy

Tolkien designed his own taxonomic system for dragons, based on two factors:[source?]

Means of locomotion

Some dragons (Scatha) had no legs, or front legs alone, and crawled like snakes.

A third type (Ancalagon, Smaug) could both walk on four legs and fly using wings. Winged-dragons only first appeared during the War of Wrath, the battle that ended the First Age, so all dragons introduced before the end of the First Age couldn't fly (such as Glaurung), although breeds of wingless dragons did survive into later ages.

Fire breathing

The Urulóki (singular Urulokë, Fire-drakes) could breathe fire. It is not entirely clear whether the term "Uruloki" referred only to the first dragons such as Glaurung that could breathe fire but were wingless, or to any dragon that could breathe fire, and thus include Smaug.

Other characteristics

The dragons also shared a love of treasure (especially gold), subtle intelligence, immense cunning, great physical strength, and a hypnotic power called "dragon-spell". The best way to talk to a dragon under the circumstances of this spell (when it was questioning you) was to not directly give it the information it wanted, as this would compromise you and your friends, but not to flat out deny it an answer, because this would anger it to violence. Therefore, the best way to talk to the dragon is to be vague and speak in riddles- apparently dragons find it hard to resist wasting time with riddles.

Dragon-fire (of the Urulóki) was hot enough to melt Rings of Power: four of the Seven Rings of the Dwarves were consumed by Dragon-fire, although it was not powerful enough to destroy the One Ring itself.[8]